Ultra wideband (UWB) is currently expected to become the preferred format for wireless communications in certain short range applications, such as personal area networks (PANs), for example. By way of example, a PAN may include a number of household electronic devices such as video recorders, personal computers, high-definition televisions (HDTVs), etc., which communicate video, audio, and other data therebetween. UWB technology is particularly attractive for PANs not only because it allows large amounts of digital data to be transmitted over a short distance at very low power, but it also has the ability to carry signals through obstacles (doors, etc.) that otherwise tend to reflect signals at narrower bandwidths and higher power.
As a result of the significant interest in UWB communications, an Institute for Electrical and Electronic Engineering (IEEE) working group has been tasked with developing standards for UWB communications in wireless PANs. In particular, the IEEE802.15.3a working group is developing a high-speed UWB physical layer (PHY) enhancement to the general 802.15.3 WPAN standard for applications which involve imaging and multimedia.
One of the leading UWB waveforms in the IEEE802.15.3a selection process is frequency hopping orthogonal frequency division multiplexing (FH-OFDM). While much progress has been made in developing the framework for FH-OFDM, many areas remain to be fully developed. One such area is interference mitigation. In one proposal submitted Nov. 10, 2003 by Batra et al. entitled “Multi-band OFDM Physical Layer Proposal for IEEE 802.15 Task Group 3a,” which is hereby incorporated herein in its entirety by reference, the use of a front-end pre-select filter in UWB receivers is proposed to reject out-of band noise and interference.
Other interference mitigation techniques have also been proposed for UWB communications. By way of example, U.S. Pat. No. 6,560,463 to Santhoff discloses a UWB communication system which includes a transceiver configured to receive a UWB communication signal, which has embedded power level data. A measurement circuit in the transceiver measures the strength of the received signal. An attenuation factor is computed that compares the measured signal strength to the data embedded in the signal. An adaptive circuit uses the attenuation factor to select a power level for a next transmission. The transceiver also has a positioning circuit that is used to accurately determine the distance from the transceiver to the source of the communication signal, and the adaptive circuit uses the distance to tune the power level for the next transmission. This patent states that the accurate selection of the lowest acceptable power level minimizes interference between communication cells, thereby increasing reliability and optimizing bandwidth utilization.
Despite the advancements in UWB communications, further improvements may be required, such as for implementing the IEEE 802.15 standards. This may be particularly true in the area of interference mitigation.